"Lights Up" will serve as the lead single off Styles' forthcoming sophomore album, which will arrive at a yet-unknown date.
The R&B-infused ballad, which was produced by Tyler Johnson and Kid Harpoon, arrived with an accompanying music video shot in Mexico.
The steamy visual depicts a shirtless Styles being surrounded by a group of men and women, while he croons lyrics such as "All the lights couldn't put out the dark/Runnin' through my heart/Lights up and they know who you are."
The single arrived a few days after mysterious "Do You Know Who You Are" billboards appeared in various locations, such as New York City and London.
They ultimately led fans to the website doyouknowwhoyouare.com, which generated positive and encouraging messages signed with "Love, H."
The former One Direction member has yet to confirm any involvement in the installation.
"Lights Up" is set to appear on Styles' forthcoming yet-untitled album, which will follow his 2017 solo debut "Harry Styles."
Last month, the English musician opened up to Rolling Stone about the inspiration behind his sophomore studio effort, pointing out the key role of psychedelics in the creative process. He joked about calling the project "Mushrooms and Blood," adding that "now there's an album title."
Although details about the full-length are still scarce, it was recorded in six weeks at Rick Rubin's Shangri-La Studios in Malibu, California, with the help of producers Jeff Bhasker and Tyler Johnson as well as a bevy of collaborators.
Ahead of the album release, discover the music video for "Lights Up" below: